1. Field of the Invention
The present invention relates to the field of safety equipment for fire fighters. During a fire, a fire fighter often has to enter a smoke filled house to search for victims. Sometimes the smoke becomes so thick that the fire fighter cannot see and find his way out. Before entering the structure, a fire fighter should have a safety rope, or "lifeline", tied to him at one end, with the other end of the line projecting outside the house so he can find his way out by following the rope. Unfortunately, the search is often performed in an emergency and the lifeline is rarely used. The present invention relates in particular to the field of safety devices for fire fighters used in searching through a structure during a fire.
2. Description of Prior Art
There are numerous types of safety equipment with lifelines for fire fighters known in the prior art. The most relevant prior art known to the inventor is represented by the following United States Patents:
1. U.S. Pat. No. 310,675 issued to Hall on Jan. 13, 1885 for "Fire Escape" (hereafter "Hall Patent").
2. U.S. Pat. No. 633,357 issued to Caulfield on Sept. 19, 1899 for "Fire Escape" (hereafter "Caulfield Patent").
3. U.S. Pat. No. 939,375 issued to Andrews on Nov. 9, 1909 for "Fire Escape" (hereafter "Andrews Patent").
4. U.S. Pat. No. 1,010,544 issued to Warner on Dec. 5, 1911 for "Fire Escape" (hereafter "Warner Patent").
5. U.S. Pat. No. 4,161,266 issued to Howarth on July 17, 1979 for "Lifeline Carrier" (hereafter "Howarth Patent").
6. U.S. Pat. No. 4,273,215 issued to Leggett on June 16, 1981 for "Safety Harness For Hunters" hereafter "Leggett Patent").
7. U.S. Pat. No. 4,877,110 issued to Wolner on Oct. 31, 1989 for "Safety Device With Retractable Lifeline" (hereafter "Wolner Patent").
8. U.S. Pat. No. 4,942,943 issued to Flaherty on July 24, 1990 for "Roofing Safety Device" (hereafter "Flaherty Patent").
The Hall Patent discloses a fire-escape comprising a frame, a reel pivoted on the frame, a cable wound around the reel, and a brake-lever pivoted also on the frame but below the reel, where one end of the brake-lever is bearing on the cable and the other end is connected to a belt fastened around a fire fighter's waist. The fire fighter can hang the cable onto a fixed object, and lower himself down by using the brake-lever to control the release of the cable.
The Caulfield Patent discloses a fire-escape comprising a drum, a cord wound around the drum, a friction-band encircling the drum and having at each end a link, a pulling device and a suspension-strap having one end attached to one link and passed freely through the other link and the other end fastened around a fire fighter's waist. The fire fighter can hang the cord onto a fixed object and lower himself down by using the pulling device to loosen the suspension-trap, thereby controlling the release of the cable.
The Andrews Patent discloses a fire-escape comprising a casing with two compartments, a reel mounted in one of the compartments, a spur wheel mounted in the other compartment, including a coil spring and geared with the reel by a pinion, a crank handle controlling the spur wheel, a cable wound on the reel and passing out of the casing and fastened back to the casing after passing through a pulley, and straps fastening a fire fighter to the casing. The fire fighter can hang the pulley to a fixed object, and lower himself down by using the crank handle to turn the reel to unwind the cable.
The Warner Patent discloses a fire escape comprising a frame, a drum with convex heads pivoted on the frame, a cable wound around the drum, a crank handle also pivoted on the frame and engaged to the drum with gears, a toggle lever with an intermediate pivot connected to the frame, a brake-controlling mechanism mounted on the frame and connected to the pivot, and a sling connected to the pivot and supporting a fire fighter. The fire fighter can hang the cable onto a fixed object, and lower himself down by using the crank handle to turn the drum to unwind the cable.
In all of the Hall Patent, the Caulfield Patent, the Andrews patent and the Warner Patent, the fire fighter's body weight is used as the descending force. The difference is the mechanism used to control the descending speed. Both the Hall Patent and the Caulfield Patent use some kind of braking mechanism which is engaged by the fire fighter's body weight and can be disengaged by the fire fighter, while the Hall Patent uses a point-friction braking mechanism and the Caulfield Patent uses a circumference-friction braking mechanism. The Andrews Patent does not have a braking mechanism but instead uses a crank handle to control the unwinding speed of the suspended cable. The Warner Patent also uses a crank handle, yet further uses a cam-friction braking mechanism which is also engaged by the fire fighter's body weight and can be disengaged by the fire fighter.
The Howarth Patent discloses a lifeline carrier comprising a container with an openable end, a closing hinge pivoted to the container at the openable end, an elongated line packed inside the container, and a blade mounted to the container which is used to attach the container to an air tank carried on the back of a fire fighter. The fire fighter can quickly release the packed line for use.
The Leggett Patent discloses a safety harness for hunters comprising a multiplicity of webs engaged to a gang connector, and a lifeline connected to the gang connector. It is particularly adapted for use by hunters who hunt from trees.
The Wolner Patent discloses a safety device with retractable lifeline comprising a housing, a drum pivoted inside the housing, a lifeline wound around the drum, a spring mechanism for biasing the drum to rotate in a retracting direction, a braking mechanism for braking extending rotation of the drum at an angular velocity in excess of some predetermined speed, and belts for fastening a person working at great heights. When the person falls, the lifeline is unwound from around the drum at a high speed which causes the drum to rotate at a high angular velocity, which in turn activates the braking mechanism. The braking mechanism will then stop the rotation of the drum to prevent further falling of the person. After each use the device must be serviced before used again because the braking mechanism is locked when somebody falls and will not self-release.
The Flaherty Patent discloses a roofing safety device comprising an upright support having self-braking mechanism and a cable assembly attached to the support. It is used for rooftop workers to secure themselves to prevent roofing injuries and death.
Overall, all the safety devices disclosed in the above discussed patents, except the lifeline container in the Howarth Patent, are used either for safely descending people from a higher place to a lower place or effectively preventing people from falling from dangerous heights. The lifelines are also designed to be heavy and strong so that they can support a person's full body weight. However in many cases when a fire fighter is working on just ground level these types of height related safety devices are really not necessary and the respective lifelines are also too heavy and time consuming to operate. In such situations, a less weighted lifeline is preferred, and the lifeline does not have to be associated with a device having a mechanism to manually control the releasing speed of the lifeline. The primary purpose of having a lifeline attached to a fire fighter fighting a fire on a ground level and within a structure is to provide him a tracer so he can use it to find his way back or others can use it to find him in case the smoke is too thick to see through. A new kind of safety device is needed to serve this purpose.